The present invention generally relates to data processing systems and more particularly to apparatus used in the control and operation of one or more peripheral devices.
The interface between a data processor and a plurality of peripheral devices has been accomplished in many different ways. As electronic logic element functionality and capabilities increase, the economies provided enable data processing system architecture to improve correspondingly. Such improved architecture may include for example the versatility of a microprogrammed control store element, as well as a so called scratch pad memory for use in storing control and status information for use in control of the devices. For a device controller, versatility and flexibility is important, and accordingly the controller should not only include apparatus by which the control store enables the operation of such controller and devices, but it should also be able to respond to instructions received from a central processor so as to facilitate processor controlled diagnostic operations. Further, the architecture should enable the more often repeated instructions to be processed, even at the expense of some additional logic, in the least time possible. Similarly, for certain often repeated arithmetic operations, such as for example that associated with the storage of information in the so called scratch pad memory, the architecture must provide for the processing to take place as quickly as possible. The system should also include efficient means by which the integrity of the information stored therein, including the instructions in the control store, be verified, and further, the controller must have the versatility to interface with a plurality of different device types. It must be able to control the operation of such different device types automatically and independent of the so-called channel by which the controller is coupled with the devices. In addition, the controller should include efficient means for addressing not only the microprogrammed control store, but also the so-called scratch pad memory.
It is accordingly a primary object of the present invention to provide improved apparatus for use in a data processing system, which apparatus is useable in controlling the operation of a plurality of peripheral devices.